1. Field of the Invention
The invention relates to a machine reaming tool, to an interchangeable head and to a shaft for a machine reaming tool, as well as to a method for the use of an interchangeable head.
2. Description of Related Art
Machine reaming tools or machine reamers are used for precision machining cylindrical bores. Individual cutters, in each case, comprise a main cutting edge or leading cut portion, and a secondary cutting edge or guide portion. The leading cut portion performs the material removal work, and the guide portion serves for guiding the tool in the bore. In order to ensure reliable guiding in all machining conditions, for example 10 millimeters or more, with a diameter, for example, of approximately 15millimeters.
A machine reamer is known from WO 01/64381 A2 which has a base body and an interchangeable head, that is to say an exchangeable reaming head. The reaming head is formed as one piece and comprises a lug for exchange adaptation, projecting beyond a rearward plane surface in the axial direction. This projecting lug is either designed in a pyramid-like manner or as a cone. On connection to the base body, the lug is inserted into a corresponding sinking of the base body, wherein clamping tabs are expanded, the tabs being separated from one another or from the remaining shaft by separating gaps or by way of expansion slots. With conical connections, additionally a hexagonal projection is formed on the reaming head and a corresponding hexagonal socket is formed on the base body, for improving the torque transmission.
U.S. Pat. No. 1,472,798 shows a reaming head with which a collar may be exchanged with the leading cut portion and a part of the guide portion, whilst the remainder of the guide portion continues to be applied.
A reaming body is shown in the Patent Abstracts of Japan in JP 07 040141, on whose front end an exchangeable head is assembled. For this, the reaming body comprises a projecting, slotted cylinder, onto which the exchangeable head is placed. The slotted cylinder is pressed on by way of a conical screw and, thus, firmly holds the head.
U.S. Pat. No. 4,166,711 and U.S. 2,303,487 show further fastening types for exchangeable tool heads.
U.S. Pat. No. 2,164,573 shows thin reaming heads, which are punched from sheet metal or may be sawn from a toothed rod. This necessitates the use of comparatively soft steels. A flexible steel is also necessary for one of the embodiments, with which the teeth are bent on machining. For this reason, one may only expect a limited accuracy of machining, particularly with the disclosed, relatively thin teeth.
A flat reaming head is described in U.S. Pat. No. 2,164,571, which may be operated in both rotational directions. The reaming head may also turned over and be used with the same rotational direction of the shaft. For this however, a large number of small teeth lying close to one another must be present, and the teeth must be ground equally on both sides along the periphery of the interchangeable head. The individual teeth in each case therefore are symmetrical and comprise two cutting edges, one for each rotational direction. The geometry of the cutting edges—with a negative rake angle—does not however permit any reaming, but a scraping machining at best.
U.S. Pat. No. 5,163,790 shows a conical mounting, wherein the conical projection comprises three cutouts. On pressing together, the conical projection is pressed apart at the locations which are not relieved and contracts at the cutouts. A fixation of a shaft in a region above the cone connection is achieved by way of this.
U.S. Pat. No. 3,087,360 describes a movable connection between the shaft and reaming head, which compensates positioning inaccuracies.